An expandable device for implantation in a body space, including an outer frame, and an inner frame slidably engaged with the outer frame. The inner frame includes a tapered wall surface. A ratchet is provided for maintaining an expansion state of the device after moving the inner frame relatively away from the outer frame so as to increase an overall size of the device, while the inner frame maintains engagement with the outer frame. The inner frame is configured to expand with respect to the outer frame in a direction perpendicular to a direction of insertion of the device into the body space.
